1. Field of Invention
The present invention relates to automatic or remotely operable pressure vessel units. The present invention is directed towards cokers having coke drums that are useful in hydrocarbon refineries; however, it can relate to closure devices and joint connectors for pipes, tanks and other various conduits where hazardous conditions exit, or, in situations where rapid opening and closing of a joint is desired.
The present invention, in part, comprises a remotely operable joint connector that is especially useful in cokers, where extremely high temperature and relatively high pressure exist. In particular this connector is especially suited for the deleterious effects of coke exposure or other xe2x80x9cdirtyxe2x80x9d operations.
2. Background of the Invention
Coke drums are structures in hydrocarbon refineries, where, inside these coke drums, heat and moderate pressure turn hydrocarbon residuum into lighter products and a hard, coal-like substancexe2x80x94coke. A pair of coke drums cycle between coking and decoking. One coke drum is coking (joints connected and operating at about 975xc2x0 F.), while the other is decoking (quenching, followed by remotely opening the joints then decoking the drum). In the decoking phase coke is removed from the coke drums by high pressure hydrostatic drilling. A drill bit is lowered into the coke drum through a drum-top deheading system and coke, cut by the drilling action, falls through a decoke chute attached to an opening in the bottom of the coke drum created when a drum-bottom deheading system removes a closure away from said opening.
Safely preparing a coke drum for decoking involves the following steps: (1) removing the working surface opening cover creating an opening in the working surface for the coke to pass; (2) remotely aligning and engaging a closure transport to the drum-bottom closure; (3) remotely energizing the drum-bottom closure to the coke drum; (4) remotely unlocking, disconnecting and separating the coke drum from the inlet pipe; (5) remotely unlocking the drum-bottom closure from the coke drum; (6) remotely disengaging the drum-bottom closure from the coke drum in a controlled manner; (7) remotely removing the drum-bottom closure from the opening in the bottom of the coke drum; (8) remotely producing and securing a passageway between the bottom opening of the coke drum to the opening in the working surface, i.e. a decoke chute; (9) remotely unlocking and moving the drum-top closure from the opening in the top of the coke drum; (10) lowering the drill bit into the coke drum through the opening in the top of the coke drum; and (11) engaging and locking the drilling head to the drum-top deheading system.
Safely preparing a decoked coke drum for coking involves the following steps: (1) remotely replacing, aligning and locking the drum-top closure to the coke drum once the drill bit is removed from the coke drum; (2) remotely decommissioning the decoke chute and replacing the working surface opening cover; (3) remotely aligning and locking the open ends of the inlet piping together, which reconnects the coke drum to the inlet pipe; (4) remotely replacing, aligning and locking the drum-bottom closure to the opening at the bottom of the coke drum.
Currently most cokers employ workers to manually perform some or all of the foregoing steps. Any of these steps can be hazardous to workers, but by far the most dangerous steps are in the transition from the coking phase to the decoking phase. Here a closed and quenched coke drum must be opened to allow the evacuation of coke from the coke drum.
Workers are most frequently harmed while performing the following steps: (1) manually unlocking, disconnecting and separating the coke drum from the inlet pipe; (2) manually unlocking the drum-bottom closure from the coke drum; or (3) manually disengaging the drum-bottom closure from the coke drum.
Coke is supposed to support itself in the coke drum when an opening is created at the drum-bottom; however, this cannot be assured. The flow of loose coke and quench water or other materials from other types of vessels can be very hazardous for workers performing functions during the opening of the vessels. This hazard exists until a secure passageway is present between the opening of the vessel and where the material is ultimately destined. In the case of a coking unit, the material is due to fall in a hole in a working surface located beneath the unit and towards an ultimate destination below the working surface. An even more hazardous environment is a coker design to produce xe2x80x9cshot cokexe2x80x9d where the coke will not support itself in the coke drum.
In many cases, the prior art sacrifices safety to provide a quick acting joint connecting means. The prior art illustrates single point failure mechanisms, where, failure of only one member could cause the integrity of the joint to be catastrophically compromised. A higher standard of safety is dictated in today""s world. The present invention provides multiple fasteners, thus, providing more safety. There is a need in industry to be able to automatically and remotely open and close a joint, and those with ordinary skill in the art can appreciate, providing redundancy in the fastening means adds difficulty.
Many companies have developed quick acting connectors, but do not provide safety. Failure of these mechanisms prompted the American Society of Mechanical Engineers (ASME) to develop rules in their Boiler and Pressure Vessel Codes that give specific rules for adding safety to xe2x80x9cQuick Actingxe2x80x9d devices. Single acting fastening means and single point failure devices must have secondary back-up retaining elements that will assure joint integrity upon failure of the single acting fastening means or single point failure devices. Such retaining elements will complicate automated operation.
In some installations, pressure vessels, pipes, and structural joints are opened and closed manually under conditions hazardous to the people performing the operation. Most prior installations utilize joint connecting means consisting of bolted flanges that are very labor intensive. The basic closing nature of bolted flanges is illustrated in the American National Standards Institute (ANSI) Publication B16.5. Other manually operated prior art for connecting joints consist of threaded, clamped and breach-lock mechanisms. These labor intensive designs are not well suited in hazardous environments.
Coke drums are pressure vessels that have openings in the top and bottom that are periodically closed and sealed. Most coke drums have manually bolted connections connecting vessel closures and other structural units to the coke drum to close and seal the coke drums internal environment. Coke drums also have manually bolted connections connecting upstream and downstream pipes to the coke drum. Manually operating these connections has proven to be harmful to workmen.
Although prior art provides simplicity, it does not provide sufficient safety. In analyzing paths of failure, the prior art contains unsafe single component failure paths that upon failure would catastrophically cause the opening of the connected joint. A logical method to create a safe connecting means is to incorporate redundancy in the fastening elements and to remove all single point failure devices from the connecting means.
Supplying redundancy in an automatic connecting means can be difficult and expensive. Those skilled in the art will appreciate the benefit of the simple automatic operation of the present invention that provides safe redundant fastening elements. The system should be operable manually as well, when necessary due to a power failure or other interruption. When compared to other automated joint connecting means, it can be noted that a significant economic benefit is realized with the present invention due to its simplicity. This simplicity directly relates to lower operating costs and shorter down time. In some processes, one day of down time can result in an economic loss far surpassing the initial cost of the automated connecting means. Simplicity in design is highly valued by end users of this technology. The prior art automated joint connecting devices, providing redundancy in the fastening elements contain overly complex mechanisms compared to the present invention. In the process of providing redundancy, the prior art sacrifices simplicity, reliability, and economy.
A number of coke drum deheading devices are known in the prior art. Most of the deheading devices do not apply a remotely operable connector. Thus, they are not fully automated are unsafe. All these devices in one fashion or another do not truly fully automate all the function associated with preparing a coke drum for decoking and/or coking; therefor, these devices are unsafe semi automated systems.
Some deheading systems only address the placement of the drum-bottom closure. By far the most dangerous manual operation is unlocking the drum-bottom closure from the coke drum. Thus, a fully remote unlocking system is desired. Other remote unlocking systems are complex and use a large number of moving parts that contribute to complexity, down time, and maintenance requirements.
A system is desired such that presently existing bolted flanges can be retrofitted for remotely controlled connecting and disconnecting. Typically, an existing manually sealed flange pair will have been disposed on vessel or pipe, such as on a coke drum. A remotely controlled connector that can utilize the manual flange already disposed on the units can realize significant cost savings as well as improved safety for the unit.
When designing truly remote functioning the designer must fully rule out the possibility of local intervention. A person may think outer space is a place that rules out local intervention, but workers are launched into space to locally repair systems that have lost their remote reliability. We all know the dangers associated with this endeavor. This invention in part and full inherently provides reliable remote functioning to coker units in many ways. The present invention in full or part will have ramifications in a number of industries, such as; Aerospace, Nuclear, Refining, Chemical, Petroleum, Food Process, and Subsea.
All aspects of the embodiments of the present invention draw attention to safety, simplicity, reliability and ease of quick maintenance.
The present invention provides a unique and safe system to remotely prepare a vessel for entry and removal of material. It is uniquely adapted to be fully remotely operable for the coking and decoking of a coke drum. Other prior art systems require some manual step and thus, present risk to workers attending them.
A goal is to develop a remotely operable coke drum deheading system that is fully automated. This system must comprise a joint connecting means embodying: safety, a means to provide a uniform sealing force to isolate internal volumes from the external environment, automatic primary remotely controlled operation, secondary manual operation, manual operation backup, predictable operation using simple parts and a small number of parts, cost effective design.
The current invention provides a unique and safe joint connecting mechanism that can be operated at a distance removed from danger and can be used to retrofit or replace existing manually bolted flanges.
In coke drums a structural unit called an inlet pipe can be attached to another structural unit called a bottom closure and must be disconnected somewhere along the inlet pipe by a joint connecting means. The present invention provides a unique and safe mechanism to remotely connect, disconnect, align and unite the bottom closure to the inlet pipe, further comprising:
a clamping device for securing the first structural unit and the second structural unit;
a clamp mover attached to the clamping device and movingly attached to the first structural unit for translating the clamping device substantially along the longitudinal axis of the first structural unit;
an aligner, attached to the first structural unit and the clamping device, whereby the aligner aligns the clamping device with the first structural unit in a position whereby the clamping device will capture and secure the first structural unit.
Part of the system to remotely prepare a vessel for entry and removal of material is a vessel closure transport to place the vessel closure from and to the vessel opening. The closure transports of the present invention are remotely operable and comprise a table for supporting the closure, a movement mechanism attached to the table for moving the table, a guiding mechanism for guiding the table to and from the vessel. The closure transport can in combination, tilt, pivot, rotate, slide, lift or lower the vessel closure. Some applications will require the vessel closure transport to the interface the vessel support deck and others will allow the vessel closure transport to interface the working surface or the coke drum.
Part of the system to remotely prepare a vessel for entry and removal of material is an apparatus for guiding material out of the vessel.
Below a coke drum""s bottom opening is a working surface containing an aperture. The aperture is opened to allow material exiting the coke drum to pass through the working surface and is closed so that workmen cannot pass though. An exit chute can be deployed and undeployed through this aperture from the working surface to the bottom of the coke drum forming a passageway for guiding material out of the vessel.
The present invention provides unique and safe system to open and close the aperture and deploy and undeploy the exit chute. The present invention also applies, in combination, the open and closing of the aperture and the deploying and undeploying of the exit chute.
When the exit chute is deployed to the coke drum it must be secured such that it doesn""t prematurely undeploy while material is exiting through it. The present invention provides a safe mechanism wherein the connector used to attach the closure to the bottom opening also attaches the exit chute to the coke drum when the closure is placed away from the bottom opening by a closure transport.
Material in coke drums may sometimes have to be drilled before it can be removed from the coke drum. A vessel penetrating tool, a drill, must be lowered through the opening in the top of the coke drum after the closure is liberated from the coke drum and transported away from the opening. The present invention provides a unique and safe vessel penetrating tool adapted to interface the joint connector to seal the vessel when the top joint connector is engaged in the closed position.
The present invention embodies a remotely operable joint connecting mechanism (xe2x80x9cconnectorxe2x80x9d) that is essential for safely connecting the coke drum to the inlet pipe, the drum-bottom closure to the coke drum and the drum-top closure to the coke drum.
The present invention provides a unique and safe system to prepare a pressure vessel completely from a remote location for entry and removal of material. It is uniquely adapted to be fully remotely operable. Moreover, embodiments of the present invention are also adapted for manual operation in the event of failure of the remote operating system.
A standard multiple bolted flange, described in ANSI B16.5, together with the present invention, produces an axial joint closing force necessary to sustain joint sealing integrity. The present invention is designed to supply the closing force with magnitude large enough to produce a contact stress on a gasket that creates a sealing barrier between the joint""s internal and external environments.
In a preferred embodiment, the present invention""s flange retaining clamp includes a clamp whose perimeter is divided into a plurality of segments, joined by redundant segment fasteners. The clamp perimeter can be cylindrical, but is not limited to a cylindrical profile. For example, joints may be rectangular or another known shape. The joint can be opened and closed remotely or manually. A preferred embodiment involves remotely operable clamp segments, operable from a location separated by distance from the joint.
The nature of the present invention provides primary remote operation without compromising secondary manual operation. Those skilled in the art will appreciate the self-contained nature of the fasteners, which allow the flange retaining clamp to be manually opened and closed quickly, with only the use of a standard wrench. A significance of the present invention""s flange retaining clamp is its ease in transition and functioning from manual to automatic remote operation.
The invention includes a remotely operated actuating means that provides a connecting force to a redundant plurality of fasteners. In a preferred embodiment of the invention, the fasteners are threaded bolts. There is a number of other joining devices that will suffice to perform the function of the threaded bolt fasteners, Cams, hooks, cables, spring loaded locking tabs, linkages, gear driven members, rack and pinion members, chain linkages and other known devices could act as a fastener to move the clamp segments into closed, sealing position. Energizing the redundant fasteners causes the clamp""s perimeter to expand and contract in an opening and closing motion, liberating or retaining the flange members. When the perimeter of the clamp segments is increased, the female taper internal diameter of the clamp segments disengages the tapered male outer perimeter of the flange hubs. The male to female tapered interface between the flange hubs and the clamp segments allows the clamp segments to act as a restraint to effectively energize and lock the flange members together allowing a seal barrier to be created. Further, the tapered flange hubs can create an axially compressing force that tends to drive the flange members into one another when the clamp is closed against the hubs. This closing occurs when the diameter of the clamp is contracted by the plurality of clamp segment fastening means. Therefore, gaskets requiring joint contact surface compression and/or seating force can be energized between the flange members creating a seal barrier to seal the vessel""s internal environment from its external environment. Stored energy in the clamp segment fastening device secures a leak tight joint.
In a preferred embodiment on the invention one of the conical make-up shoulders is replaced by a substantially straight non-angled make-up shoulder, such as that disposed on manually bolted flanges. This arrangement allows an existing manually bolted flange to be retrofitted for remotely controlled operation by removing the manual bolts and disposing the present invention about an existing flange. Typically, an existing manually sealed flange pair will have been disposed on a pair of structural units to be joined. Hazardous conditions of or about the joining of this flange pair or the benefit of decreased joint connecting and/or disconnecting time gives birth to the need for remotely controlled devices, such as the present invention. Since the present invention can utilize a manual flange already disposed, significant cost savings is realized.
A preferred embodiment of the present invention""s clamp provides a remotely operable mechanism to assure uniform closing force along the entire perimeter of the clamp segment to the flange member contact surface interface. This unique feature incorporates, clamp segments adapted to make controlled contact (xe2x80x9cCC clamp segmentsxe2x80x9d) at or about the midpoint of the clamp segment farthest away from the clamp segment fastening devices and also utilizes guide members, adapted to act on the clamp segments to guide the contact of the clamp segments with respect to the flange members producing a controlled predictable contact. This controlled contact, together with CC clamp segments uniformly preloads the entire joint by initiating contact between the clamp segments and the flange members substantially near or about the clamp segments midpoint farthest away from the clamp segment fasteners. The actuating device member, acting on the clamp segment fastening device, provides a closing force, transmitted into the clamp segments, reducing the clamp""s perimeter and causing the CC clamp segments to resiliently flex substantially near or about the clamp segments"" midpoint. This resilient flexing occurs as the CC clamp segments are energized and forced to engage the flange members by the clamp segment fastening devices. The closing force first provides connecting preload at or near the CC clamp segments"" midpoint, then continuously provides the preload force closer and closer to the clamp segment fastening device as the CC clamp segment is flexed about its midpoint. This unique feature causes the clamp segment fastening device""s force to be uniformly distributed along each entire clamp segment against the flange hubs"" contact surface. The uniform preload at the contact surface, in turn, supplies a uniform sealing force on the flange member to gasket member contact surface, creating a barrier between the joints"" internal and external environments.
Moreover, a unique way to assure the uniform preloading can be effectively incorporated with a remotely operated joint opening and closing mechanism. A preferred embodiment utilizes guide pins, attached to the clamp segments. These guide pins are restricted to travel in passageways fixed with respect to at least one flange members. The fixed motion of the guide pins, in turn, guides the radial motion of the clamp segments, relative to the flange members. This motion causes the clamp segments"" midpoint to return to the flange members at a predictably controlled location every time the clamp segments are remotely actuated from the clamp segments"" open position to the clamp segments"" closed position.
When the clamp segments are secured to the flange members, friction between the flange hubs and the clamp segments tend to lock the clamp segments onto the flange members. CC clamp segments are resilient and when energized and forcefully flexed into engagement with the flange members energy is stored. This energy tends to return the clamp segments to their free state away from the flange members; thereby, producing a relative unlocking force between the clamp segments away from the flange members that overcomes the friction force holding them together. Those of ordinary skill in the art will appreciate the substantial benefit of this feature, which reliably overcomes the locking friction force between the clamp segments and the flange hubs, and the importance of this feature to the effective remotely controlled connecting and disconnecting of a joint.
In cylindrical geometry, clamps retaining flange members with an internal diameter less than 36 inches will preferably have two clamp segments. Larger diameter flange members will preferably be retained by clamps having several segments. Each clamp segment adapted for and conjoined by clamp segment fastening devices that are, in turn adapted for remote and/or manual actuation.
In some remotely operable connecting applications, such as joints in a coke drum, the low number of cycles (measured by half days), coupled with low contact stress at the clamp segment to flange hub interface, makes wear of this interface an insignificant factor when determining the life of the coke drum. Those skilled in the art will appreciate the present invention""s flange retaining clamp that reduces such wear at the mating surfaces between the flange hubs and the clamp segments. This feature addresses the reduction of wear by decreasing the length of dynamic engagement at the mating surfaces, coupled with a reduction in contact stress at the mating surface engagement. CC clamp segments adapted to maximize initial area contact mating with flange members, creates a contacting interface for a remotely controlled flange retaining clamp.
In the closed position of the present invention""s clamp, the flange hubs have a generally male conical profile that mates with the clamp segments"" generally female conical profile, sharing the same conical vertex. Sharing the same conical vertex determines the overlaying of the mating surface throughout a substantial part of the 360 degree conical contact length; wherein, the available mating contact surfaces of the clamp segments"" come in contact with mating flange hubs"" surface. In the prior art, wear was of concern when the clamp segments are dynamically moved onto the flange hubs from the open position to the closed position. Such wear is not observed in the current invention.
The present invention""s flange retaining clamp discounts wear with a unique contacting behavior. CC clamp segments mating with flange members, in effect, significantly align the free state conical vertex of the clamp and flange hubs"" conical contact interface; wherein, the flange members are retained but energized by the clamp. This close alignment significantly reduces the length of dynamic engagement between the clamp segments and flange hubs, and turns the initial line contact, associated with prior art mating members, into a large area contact. These two effects eliminate wear of the clamp segment to flange hub contact surface as the clamp segments are forced onto the flange hubs driving the flange hubs"" conical apex and clamp segments conical apex into substantially alignment as the clamp closes and the gasket is sealingly compressed by the flange members.
The present invention""s flange retaining clamp is a self-contained mechanism. To function properly, the present invention""s clamp does not require external devices, such as foundation reaction points or motion limiting devices.
The clamp segments can be further self-contained by incorporating the passageways for the pivot pins, and other clamp support passageways, into a self-containing support ring or plate, which is spring loaded to the clamp segments at the guide pins"" locations. Such self-containing rings fix the orientation of the passageways, such that the clamp segments are guided from the open position to the closed position, relative to the flange members, and relative to each other, to assure proper connection and disconnection of the joint. This self-contained clamp assembly could then be removed as a single unit from the flange members quickly and easily for preventative maintenance. This approach is especially useful in a subsea environment where remote controlled vehicles could retrieve this modular clamp assembly for easy transport to the surface, and replace the assembly with a new assembly, leaving flange members at their subsea location.
The clamp segment fastening device is the entire device used both to connect together and to actuate the clamp segments, securely holding the gap between the clamp segments closed, and can be of any known construction. For safety reasons the clamp segment fastening device elements should be redundant and, therefor, not contain a failure path that could cause an opening of the gap upon failure of any one component. There are a number of other clamp segment fastening devices that would suffice to perform the function of the clamp segment fastening device. Cams, hooks, cables, spring loaded locking tabs, linkages, gear driven members, rack and pinion members, chain linkages, swing bolts, and other known devices could act as a clamp segment fastening device to bring together the clamp segments. Although the present inventor realizes that there are a number of clamp segment fastening devices available, the current clamp segment fastening devices were selected because of their many benefits listed below.
In prior art, the transition between remote and manual operation is complicated. Some remotely operated mechanisms must be disconnected before manual operation can occur. The manual operation of prior art is both labor intensive and complicated by the remote operation. The current clamp segment fastening device can be energized to either open the clamp gap or close and lock clamp gap both automatically by remotely actuable drive member or by manual operation with ease and without disconnecting any components. Primary remote operation is married with secondary manual operation in a unique and simply manner. Those skilled in the art will realize the ease in transition between remote and manual operation and the ease of the manual operation of the current clamp segment fastening device.
The clamp segments can be uniquely remotely opened and then remotely closed and then remotely locked to sealingly retain flange members. Without local intervention, it can then be remotely unlocked and then remotely opened. This process could be repeated ad infinitum at long distances.
The energy supplied to the clamp segment fastening device by the remotely actuable drive member is positively stored by the clamp segment fastening device, thus securing the gaps between the clamp segments and locking the flange retaining clamp onto the flange members even if the remotely actuable drive member is disconnected. This feature is required to safely secure the sealed joint independent of the remotely actuable drive member.
Energy stored in the clamp segment fastening device can be increased or decreased manually even after it has been locked.
The fastening means can be energized by any known actuable drive member, such as hydraulic or pneumatic cylinders or motors. Known mechanical advantage devices, such as; gears, wedges, linkages and cams could be incorporated with the actuable drive member.
The clamp segment fastening device interacts with the clamp segment in a self-contained assembly. This assembly does not require external anchors or reaction structures to operate. Also, the clamp segment fastening device will self-limit the opening motion of the clamp segments; therefor, motion limiting devices are not required.
To safely conjoin and secure the clamp segments in the closed position, the clamp segment fastening device has redundant joining elements. In a preferred embodiment of the current invention, these redundant joining elements are a plurality threaded bolts. If one bolt were to fail a backup exists.
The plurality of joining elements can be energized by a single remotely actuable drive member.
The design of the present invention""s flange retaining clamp allows for dry assembly of the component parts of the clamp. That is, no grease or other lubricant is required during assembly. Further, depending upon the material from which the components are manufactured, the present device can be utilized in environments up to 1800 F.